Two hundred feet above the subterranean lake, the diversion wall at the mouth of the eastern limestone trench was breaking apart because the water refused to run like ordinary water.
Chaska crouched on the slick rock shelf above the sluice with her left arm strapped tight against her ribs and her right hand pressed flat against the vibrating clay-and-strut baffle they had wedged across the lake chute.
“It’s not a steady flood!” Chaska shouted over the groaning stone as Corporal Vane and young Tor jammed another sack of gravel against the leaking lower seam. “Feel the timing!”
Down in the trench, the warm mineral current from the drained spring was surging forward and sucking backward in heavy, ten-second heaves—push for four, hold for two, draw for four—pulled by the resonance of the hanging clapper below and the synchronized breathing of the soldiers on the lake shore. Every time the bell drew breath below, the water in the upper chute slammed against the clay baffle like a battering ram.
With a wet, grinding wrench, two of the alloy struts Chaska had donated from her cargo-gliding frame tore loose from their clay sockets. Muddy sulfur water spouted through the gap as thick as a man’s thigh, splashing back across the floor of the warm cavern and threatening to undercut the mortar walls of the four temporary animal basins.
